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Message-ID: <3.0.1.16.19990830144810.08efd61c@mail.cc.kuleuven.ac.be>
Date: Mon, 30 Aug 1999 14:48:10
To: rsgb_lf_group@blacksheep.org
From: "Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be>
Subject: LF: Multiple Tuned Vertical : some more maths
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I did some calculations on a more 'real-world' model of a MTV antenna,
assuming that the second tuned section has its own radial system (loss
resistance = R2)

             +------+---------+
             |      |         |
            +-+   -----      +-+
         L' | |   ----- C    | | L'
            | |     |        | |
            +-+    +-+       +-+
             |     | | R1     |
             |     +-+       +-+ 
             |      |        | | R2
        -----+      |        +-+
   Z =              |         |
        ------------+---------+

If we further assume that :
- both inductors are equal and have the double reactance as C
- the reactances of C and L are large compared to R1 and R2

The the result of the calculations is Z = 4 x R1 + R2

That means that only the 'R1' component is quadrupled, the 'loss
resistance' R2 of the second tuned section is just added !

I don't want to bore the whole LF-group with the maths, but I'm willing to
mail it direct to those interested (it's only about 5 lines of basic math).

73, Rik  ON7YD


Rik Strobbe  ON7YD
rik.strobbe@fys.kuleuven.ac.be
Villadreef 14  B-3128 Baal  BELGIUM   (JO20IX)